From "Supernatural: Jus in Bello (#3.12)"
Lilith killed everyone. She slaughtered your precious virgin plus half a dozen other people. So after your big speech about humanity and war, turns out *your* plan was the one with the body count. Do you know how to fight a battle? You strike fast and you don't leave any survivors, so no one can go running to tell the boss. So next time, we go with my plan.